1. Field of the Invention
The present invention relates to a thermal head.
2. Description of the Prior Art
In a prior art thermal head, as shown in FIGS. 1A and 1B, a heat insulation layer 2 is formed on a ceramic substrate 1, and a heat generating resistor 3, an electrode layer 4 and a protection layer 5 are stacked thereon.
With this structure, however, a surface of the thermal head is flat and good contact between a heat generating area and a thermal record paper is not attained, and hence a high quality of print is not achieved. To avoid the above problem, a heat insulation layer 6 is formed only at the heat generating area as shown in FIGS. 2A and 2B so that the heat generating resistor 3 protrudes from the surface of the thermal head to attain good contact between the heat generating area and the thermal record paper.
However, in the above structure, because a plurality of heat generating resistors are fixed on one plane, some of the heat generating resistors make good contact to the thermal record paper while others do not, depending on the unevenness of the surface of the thermal record paper. As a result, print density is not uniform.
In a thermal transfer printer in which a thermal transfer ribbon is placed between the thermal head and a plane paper, non-uniformity in print density is a serious problem because of a requirement for a high print quality.